The HPV vaccine is very safe and very effective in preventing cervical cancer, according to two large reviews that support routine vaccination of adolescents against human papillomavirus.
HPV is the most common sexually transmitted infection and can cause genital warts. Merck’s Gardasil vaccine, the first version of which was approved in 2006, protects against nine strains of HPV that cause cancer.
Nearly 60 randomized controlled clinical trials with 160,000 participants, considered the gold standard of scientific research, indicated that the HPV vaccine is effective in preventing infection, as well as precancerous lesions of the cervix and genital warts. The two papers, recently published by the highly respected British Cochrane Review team, also included 225 observational studies of more than 132 million people around the world. Collectively, the studies showed that girls who were vaccinated against HPV before age 16 had an 80% lower risk of cervical cancer.
“The vaccine works. Full stop,” said Dr. Linda Eckert, a professor of obstetrics and gynecology at the University of Washington and an expert on the causes of cervical cancer. “The vaccine is safe. Full stop.”
Eckert, who was not involved in the reviews, praised them as “methodically rigorous,” “robust” and “gold standard.”
The new reports are supported by recent real-world findings. In late November, an Australian cervical cancer research organization announced that, almost certainly due to HPV vaccination, there were no new cases in 2021 in women under 25, a milestone not seen since data was collected starting in 1982. Last year, Scotland’s public health agency found that there were no new cases of cervical cancer in women fully vaccinated when they were young.
“We did a search on social media, looking at all the things people said HPV was associated with,” said Jo Morrison, lead author of the Cochrane reviews and a consultant in gynecological oncology at Somerset NHS Foundation Trust in England. According to his team’s articles, claims included that the vaccine caused infertility, chronic fatigue syndrome and paralysis. “What we found was that the evidence shows very clearly that there is no association with the various things that people are concerned about,” he said.
Specifically, the team found that serious adverse health outcomes were rare and occurred at similar rates regardless of whether trial participants received the vaccine or a placebo.
The revisions come as Health and Human Services Secretary Robert F. Kennedy Jr., an anti-vaccine activist, has increasingly stepped up scrutiny of childhood immunizations in general.
Kennedy has benefited financially from vaccine injury lawsuits against Merck, the maker of the HPV vaccine Gardasil. In 2019, he called Gardasil “the most dangerous vaccine ever created.” Pressed during his Senate confirmation hearing by Sen. Patty Murray, D-Wash., Kennedy declined to say whether the vaccine was safe.
HHS did not respond to a request for comment.
The Centers for Disease Control and Prevention, in guidance established before Kennedy’s tenure at HHS, recommends vaccinating boys and girls against HPV between ages 11 and 12, before they become sexually active. More generally, the agency recommends Gardasil for ages 9 to 26. People up to age 45 are eligible for the vaccine.
The HPV strains targeted by Gardasil can cause multiple cancers in both men and women, including anal, vulvar, oropharyngeal (back of the throat), vaginal, and penile cancers. About 48,000 cases of HPV-related cancer are diagnosed annually in the United States, including about 13,360 cases of cervical cancer.
However, since HPV vaccination began, the U.S. cervical cancer rate plummeted 65% between 2012 and 2019 among women in their early 20s, the first U.S. cohort to receive the vaccine, according to a 2023 study from the American Cancer Society.
Morrison said the Cochrane reviews were probably only able to determine with certainty that the HPV vaccine prevents cervical cancer because other HPV-related cancers generally take longer to develop. For now, it’s unclear whether vaccination reduces rates of other cancers, he said.
Concerns about Gardasil have persisted since it was first approved two decades ago.
Morgan Newman, 35, of Norwalk, Iowa, was offered the HPV vaccine at a doctor’s appointment the year Gardasil was approved. So, at age 16, he went against his parents’ wishes and refused, feeling that the vaccine was too new and that he didn’t know enough about it.
Eight years later, she was diagnosed with cervical cancer. He underwent chemotherapy and radiation, but the cancer metastasized two years later.
“They take you to the brink of death,” she recalled of the brutal treatment that led to her infertility.
Nearly a decade after remission, Newman is an outlier in continuing to survive stage IV cervical cancer.
“Cancer is a gift wrapped in barbed wire,” he said, noting that he lives with lymphedema, a permanent side effect of chemotherapy that causes painful fluid retention. “I’m grateful to be here, but I want to make sure everything I do has a purpose behind it.”
She has become a social worker and volunteer for Cervivor, a nonprofit cervical cancer advocacy organization.
Newman recalled his thinking as a teenager about the possibility that he could ever develop a vaccine-preventable cancer. “I told my mom, ‘No, that will never happen to me,’” he said.
According to data from the CDC’s annual survey, HPV vaccination rates, altered by the Covid pandemic, stabilized among youth ages 13 to 17 from 2022 to 2024. About 78% of these adolescents eventually received at least one dose and 63% completed multi-dose vaccination. Meanwhile, rates of other vaccines that the CDC recommends for adolescents increased during this period and exceeded 90%.
A 2024 study published in The Lancet Regional Health found that white families in the US and those with higher incomes were less likely to intend to vaccinate their children against HPV; Security issues were the most common reason.
Among the concerns is that providing a vaccine against an STI could eventually lead to children taking sexual risks, although research by Harvard University has found no evidence to support this.
A Seattle mother who asked that her name not be used for privacy reasons said she hesitated when her pediatrician recommended Gardasil for her teenage sons, now 15 and 17 years old.
“I remember thinking, well, my kids aren’t sexually active,” the 49-year-old mother said of the prospect of getting them vaccinated against an STI. “So I thought, well, I better do it. Let’s cover all the bases.”
